Method of using a protective test strip platform for optical meter apparatus

ABSTRACT

A test strip platform for a testing apparatus of the type using test strips, wherein the platform has a shroud defining a strip track for positioning an inserted strip over an optical aperture for making analytical determinations. The platform has a hood permanently mounted to the shroud for overlying the optical window and protecting the testing apparatus optics. The strip track has stabilizing members for holding the strip in testing position. The hood provides camming members for guiding the leading edge of an inserted strip into cooperative engagement with the stabilizing members for ensuring proper insertion of the strip.

This is a division of application Ser. No. 9/448,711, filed Nov. 24, 1999 now U.S. Pat. No. 6,458,326, which is incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The invention relates generally to analyte determinations, more specifically to reflectance based optical monitoring systems, such as that employed in enzyme-based blood analyte chemistry analysis on disposable strips (e.g., blood glucose testing systems), and still more specifically to an apparatus for protecting the optics of such systems from contamination and ensuring proper strip insertion into a monitoring system.

BACKGROUND OF THE INVENTION

Portable analyte monitoring systems, including blood glucometers, are well known in the art. In the case of blood glucometers, these monitors are typically portable meter apparatus that are employed for personal monitoring of blood glucose levels, typically by diabetic patients. Since the 1970's, these devices have gained increasing popularity and acceptance for personal home use in managing when insulin injections are needed by diabetics. These meters have recently become increasingly portable, accurate and convenient due to advances in electronic, optical and test strip chemistry technologies.

The most common type of glucometer used today is based on reflectance optics in conjunction with a disposable, one-use test strip. In use, a small strip carrying reagent chemistry which reacts with blood is employed, such as that described in U.S. Pat. No. 5,296,192, the contents of which are hereby incorporated by reference herein. When fresh whole blood, typically from the lanced finger of a patient, is applied to the test strip, an enzyme-based reaction takes place producing a color change which typically progresses chromatically in proportion to the concentration of glucose present in the blood sample. After blood is applied and the reaction is underway, the strip is then inserted into the monitoring apparatus, and optical reflectance is used to measure the chromatic change. Once the apparatus has determined that the reaction is sufficiently complete, which optimally occurs when the reaction is stabilized, a reflectance measurement is converted through software in the monitoring apparatus into a glucose measurement, typically in mg/DI, and reported on a display to the user.

Such optical monitoring apparatus rely on proper insertion of the strip to ensure alignment of a portion of the strip containing the blood sample and reagent chemistry with the meter optics for accuracy. Further, if the optics become contaminated by blood or other foreign matter, accuracy is also compromised. Because these monitoring apparatus are used by diabetic patients, who frequently suffer sight and motor coordination impairment, it is important that the monitoring apparatus facilitates proper introduction and guided alignment of the strip, as well as protects the optics from contamination. Because of their portability, these apparatus will be subjected to various harsh environments and handling, which could contaminate the optics.

Prior art apparatus are inadequate for addressing these needs. One popular meter, sold under the name ONE TOUCH is described in U.S. Pat. No. 5,843,692. This device requires that the strip be first inserted into the meter and then blood is applied to the strip. This method is inconvenient for the user, as he or she must align a punctured finger with the test site on the strip while it resides in the meter. Consequently, this can result in the inadvertent spillage of blood onto the meter, and subsequently contaminate its optics. Frequently, this will occur when a large blood drop is deposited directly onto the strip. This device also utilizes a door to shield the optics from ambient light during use, which protects the optics when the meter is not in use. Unfortunately, this adds to the testing process the steps of opening and closing the door. Further, because the optical systems of this apparatus requires a door to block ambient light, breakage of the door renders the apparatus unusable.

SUMMARY OF THE INVENTION

There is a need in the art for a portable monitoring apparatus which will ensure proper strip alignment with its optics, and which will protect the optics from contamination.

The present invention relates to a method and apparatus for ensuring proper strip insertion into and alignment with an optical reflectance meter, while simultaneously protecting the optics of the meter.

According to one aspect of an illustrative embodiment of the invention, a test strip receiving member, or shroud, has an optical window which is disposed above the optics of the monitoring apparatus. A protective optics cover, or hood, is provided on the shroud to protect the optics underlying the optical window from contamination by foreign matter.

According to a further aspect of an illustrative embodiment of the invention, the shroud is provided with a track for guiding the strip to the testing position. The shroud provides fingers for engaging cooperative indents on the strip for tactile indication of proper testing position of the strip.

According to a further aspect of an illustrative embodiment of the invention, the protective hood is permanently mounted to the shroud and is provided with camming members for guiding the leading edge of an inserted strip such that it will be properly received by the fingers and directed into proper testing position.

These and other features and advantages of the present invention will be easily understood with reference to the Figures depicting an illustrative embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a portable monitoring apparatus with the inventive test strip platform of the present invention, depicting the insertion of a prior art test strip.

FIG. 2 is an isometric exploded view of an illustrative embodiment of a test strip platform according to the present invention.

FIG. 3 is an isometric view of the bottom surface and camming members of the hood.

FIG. 4A is a top view of a prior art test strip.

FIG. 4B is a bottom view of a prior art test strip.

FIG. 5 is a cross sectional view of the shroud of FIG. 2 taken along line A—A with a cross sectional view of the hood taken along line A′—A′ after permanent mounting of the hood on the shroud.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to an illustrative embodiment illustrated of the invention as depicted in the drawings.

Referring to FIG. 1, there is depicted a portable test apparatus 2, such as the type used to measure blood glucose in whole blood, available under the trade name PRESTIGE LX manufactured by Home Diagnostics, Inc. of Ft. Lauderdale, Fla. The housing of the apparatus contains microprocessor based electronics for computing blood glucose concentrations from a sample applied to a test strip 200. The apparatus 2 has a display 4, which may be an LCD display, for reporting calculations and other information to the user. The strip 200 is inserted into a strip-receiving platform 6, which will be discussed in greater detail hereinbelow.

FIG. 2 is an exploded view of the platform 6 shown in FIG. 1. The platform is removable from the apparatus 2 to facilitate cleaning to remove blood and other contaminants, and allows access to a window (not shown) which covers the optics of the apparatus. Removal of the platform 6 permits the optical window to be cleaned to ensure optimal performance of the apparatus 2. The platform 6 is comprised of two major components, which are permanently joined together. These components are the shroud 10 and the hood 100, which are discussed below in turn.

The shroud 10 receives the strip and guides it into position for the meter to operate properly. The shroud 10 has a cavity 12 which is lower than the top surface of the shroud and is dimensioned laterally to cooperatively receive a strip in snugly sliding, clearance fashion to ensure lateral stability while allowing advancement of the strip. On either side of the cavity 12 is a stabilizing member, or finger 14, which extends into the cavity diametrically opposed to an opposite finger. These fingers 12 bias a strip inserted into the cavity 12 into the proper position for the apparatus optics to make a good reading. When inserted, a strip will be snugly held against the bottom surface of the cavity 12 such that a color spot, described below, is held above an optical aperture 20. The optical aperture 20 is positioned above the optics of the apparatus when the platform 6 is secured in the meter apparatus 2. The shroud 10 also has means 16 for permanently attaching the hood thereto, and also means 18 for removably attaching the platform 6 to the meter apparatus housing.

The second major platform component is the hood 100, as further depicted in FIG. 2. The hood 100 serves to both protect the optics of the meter which underlie the optical aperture 20, and also to help guide a strip into proper testing position, as will be discussed hereinbelow. The hood has means 102 for permanently attaching it to the shroud 10. As depicted, means 102 on the hood mate with cooperating means 16 on the shroud for permanent mounting. These features as depicted are intended to be illustrative, and may take the form of any of a number of mechanical expedients and processes known in the art for rendering a permanent attachment between components, for example gluing, bonding, ultrasonic or RF welding, or very rigid mechanical locks or detents.

Turning to FIG. 3, the underside of the hood 100 is shown. A viewing notch 104 can be provided in order to allow the user to witness the advance of the leading edge of an inserted strip when the hood 100 is permanently attached to the shroud 10. Further provided are camming members 106, which provide a downward ramping surface for urging the leading edge of an inserted strip under the fingers 14 of the shroud when the hood 100 is permanently attached to the shroud 10. This feature will be further addressed with respect to FIG. 5, which is discussed after a brief description of a prior art strip shown in FIGS. 4A and 4B.

Referring to FIG. 4A, the upper surface of a prior art test strip, such as that described in U.S. Pat. No. 5,296,192, is depicted. The strip 200 has a sample port or test spot 202, onto which blood is applied before introducing the strip into the apparatus 2. The strip 200 also has indents 204 or other surface feature which cooperate with the fingers 14. Of course, other cooperating structure can be provided in the platform to engage similar indents, which can be located anywhere on the strip. The indents provide a tactile guide for indicating when the strip has been inserted into the correct testing position (i.e., with the color spot as described below oriented over the optical aperture 20 of the shroud), and also provides a resistance for holding the strip in this position. The resistance is easily overcome by manually pulling on the strip, but is sufficient to retain the strip in the testing position if the meter is physically reoriented or jarred during testing. The strip 200 can also have a band 206 which can be used by the meter apparatus 2 to optically detect when the strip has been fully inserted. Full insertion usually indicates the testing position, and will correspond to the position where the indents 204 are engaged by cooperating structure such as those on fingers 14. The band 206 is also viewable through viewing notch 104 as seen in FIGS. 2 and 3 to allow the user to confirm that the strip has been inserted properly. As there is no band on the bottom side of the strip 200, the user can witness through the notch 104 whether the leading edge contains shows band 206 and thus whether the strip has been inserted properly.

FIG. 4B depicts the bottom surface of the strip shown in FIG. 4A. A viewing port or color spot 208 is located substantially directly beneath the test spot 204. When fluid containing analyte is applied to the test spot 202, it passes through an element containing chemistry in the strip producing a color change, which, if sufficient sample has been applied, can be visually verified by viewing the color spot 208 before inserting the strip 200 in the testing apparatus 2. The color spot 208, when the strip is inserted into the correct testing position is located over the optical aperture 20 in the shroud such that meter optics can access the color spot 208.

Turning now to FIG. 5, there is shown a cross sectional view of the platform 6, showing the shroud 10 and hood 100 permanently joined to each other. The cross sections of the shroud 10 and the hood 100 are taken along section lines A—A and A′—A′ respectively. As can be seen, the cavity 12 of FIG. 1 corresponds to a strip track 22, wherein a strip may be inserted along the direction of arrow B. As can be appreciated, the leading edge of an inserted strip will encounter the camming members 106 and be deflected downwardly so that the leading edge passes beneath the fingers 14. As shown, protuberances 14 a provide structures for cooperating with indents 204 in the prior art strip depicted in FIGS. 4A and 4B. As further shown, optical aperture 20 overlies meter optics 300, which are depicted in schematic form. As can be appreciated, the hood portion 100 of the platform protects the optics 300 from contamination.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only an illustrative embodiment has been shown and described and that all changes and modifications that come within the spirit and scope of the invention are intended to be protected. For example, application of the present invention is not limited to optical reflectance meters or to meters which measure blood glucose levels, but will find application in any meter type which requires insertion of a test strip. 

1. A method of performing an analytical determination comprising the steps of: providing a testing apparatus comprising: a shroud portion, said shroud portion comprising a strip track, an optical aperture along said strip track, and at least one stabilizing member extending into said strip track in the vicinity of said optical aperture; and a hood portion immovably attached to said shroud portion over said strip track so as to protectingly overlie said optical aperture, said hood portion comprising at least one camming member descending into said strip track: providing a test strip having a leading edge and a color spot; applying a material containing analyte to said test strip so as to cause an optically measurable change at said color spot; introducing a said test strip into said strip track; advancing said test strip such that said at least one camming member and said at least one stabilizing member guide said test strip into a testing position; and while said test strip is in said testing position, optically accessing said color spot through said optical aperture to make the analytical determination.
 2. The method of claim 1, further comprising the step of said at least one camming member downwardly deflecting said leading edge of said test strip so that said leading edge passes beneath said at least one stabilizing member.
 3. The method of claim 1, wherein said test strip has at least one indent and said at least one stabilizing member has at least one protruberance engaging said at least one indent when said test strip is in said testing position.
 4. The method of claim 3, further comprising the step of: said at least one protruberance engaging said at least one indent to provide a tactile indication when said test strip is inserted into said testing position.
 5. The method of 3, further comprising the step of: said at least one protruberance engaging said at least one indent to provide a resistance for holding said test strip in said testing position. 